A relative clause gives more precise information on
the main clause. Object of this more precise information
can be the subject, the object or the whole context.
The relative clause is connected to the main clause
by a relative noun.

some
relative clauses that refer to one object

The
lady who
sells flowers is my friend.
The book that
you where looking for is under the table.
The man whom
we met in London is a web designer.
The garden that
you like so much is right around the corner.
The wall behind which
you hear the noises is painted black.
The place where
he was born didn't exist anymore.

some
relative clauses that refer to a context

He
didn't write a letter to her what
made everything more complicated.
They ate as if
they hadn't had any food for weeks.
He had shouted at her what
made her really angry.
She had deceived him what
made him loose his temper.